Supporting mobile ad-hoc network (MANET) and point to multi-point (PMP) communications among nodes in a wireless network

ABSTRACT

Nodes in a wireless network participate in either point-to-multipoint (PMP) or MANET/mesh communications with other nodes on one or more shared channels of the network. A first or base station node transmits a downlink signal having a time frame structure of determined duration to a number of second or subscriber nodes. Portions of the frame structure establish (i) first time periods during which messages are transmitted from the first node to the second nodes, and (ii) second time periods during which messages are transmitted from the second nodes to the first node, using the PMP protocol on one or more shared channels or subchannels of the network. Other portions of the time frame structure establish third time periods during which nodes communicate with one another using the MANET/mesh protocol on the shared channels or subchannels, while avoiding interference with messages transmitted under the PMP protocol.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 11/991,030 which was filed under 35 U.S.C. §371 on Mar. 12,2009 now U.S. Pat. No. 7,821,994. The parent '030 application claimspriority under 35 U.S.C. 119(e) of U.S. Provisional Patent ApplicationNo. 60/816,038 filed Jun. 23, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to wireless communication systems, particularlypoint to multi-point (PMP) and mesh or mobile ad-hoc networks (MANET).

2. Discussion of the Known Art

Point to multi-point or PMP protocol communication equipment is used invarious broadband wireless systems. The systems are typicallystandards-based, or are certified by industry trade groups, e.g., WiMAXForum certified, IEEE 802.16-2004, IEEE 802.16d, IEEE 802.16e-2005, IEEE802.16e, and HIPERMAN.

Communication equipment operating under mesh or mobile ad hoc network(MANET) protocols is often used in military applications. An example ofa mesh network is given in the original IEEE 802.16d standard which, inaddition to a PMP mode, defined a mesh mode as well. The standardallowed for only one of the two modes to be selected for networkoperation, and did not allow for both modes to operate simultaneously.See, e.g., F. Jin, et al., Routing and packet scheduling in WiMAX meshnetworks, Fourth International Conference on Broadband Communications,Networks and Systems, BROADNETS (2007). The mesh mode, which was insubclause 6.2 of the original IEEE 802.16 standard, was withdrawn fromthe latest version (May 29, 2009) of the standard, however.

Allocations of new radio frequency (RF) bands for operation of wirelesscommunication networks are often difficult to obtain. Because of thisand for other reasons, it would be desirable to allow multiple networktopologies or protocols (e.g., PMP, and mesh or MANET) to co-exist onany one channel or channels of a wireless network without causinginterference among different communications taking place under eachprotocol. For example, a relay station (RS) may need to extend thecoverage of an existing wireless PMP base station (BS) in order to allowa given node outside the existing coverage to join the network as a newsubscriber station. In such a case, the BS and the RS could link withone another using the mesh protocol to coordinate the use of networkchannels, and thus allow the RS to operate as a PMP base station withrespect to the new subscriber station.

In another example, two military convoys each employing a PMP system mayneed to maintain wireless connectivity between vehicles of theirrespective convoys while in motion. As the base stations of the twoconvoys pass near one another, it would be desirable for the two basestations to implement a MANET in order to coordinate their movementswith one another while maintaining their individual PMP networks.

Yet another example is a military training exercise in which it becomesnecessary to gather performance data from thousands of RF collectiondevices in the field. Each soldier may be provided with a wirelessdevice for relaying data collected during the exercise. Such deviceswould operate most efficiently in a PMP network, but some of the devicesmight be outside PMP coverage and need to forward data through otherwireless devices (other than a BS) so as to maintain connectivity.Again, a MANET or mesh network operating simultaneously on the samechannel with the PMP network would meet such a need. The foregoingexamples are merely illustrative and are not intended to limit thevarious circumstances in which the present invention may be usedadvantageously.

U.S. Pat. No. 7,031,274 (Apr. 18, 2006) discloses a method of enablingsystems following the IEEE 802.11 protocol to interoperate with wirelesslocal area networks (WLANs) that use an otherwise incompatibleHIPERLAN/2 standard, on a common transmission channel. Further, U.S.Pat. No. 7,133,381 (Nov. 7, 2006) describes a method by which stationsoperating under an enhanced, IEEE 802.11e standard, can preventinterfering transmissions from stations that do not practice the 802.11estandard.

U.S. Pat. No. 7,630,402 (Dec. 8, 2009) discloses a media access controlunit with specified software and hardware for the purpose ofimplementing the mentioned IEEE 802.16 standard protocol. The patentdoes not suggest any variance to the protocol such as would allow bothPMP mode and mesh mode communications to occur simultaneously on an IEEE802.16 standard wireless network, however.

U.S. Pat. Appl'n Pub. No. 2008/0151802 (Jun. 26, 2008) concerns powersaving techniques within an IEEE 802.16 network including relay stations(RS) as defined by the IEEE 802.16j standard, wherein end users (mobileand fixed) may conserve power and achieve longer battery life. A “MAP”structure is received at a RS and modified prior to retransmission toeffect better power utilization in the network. The publication does notsuggest any change to the underlying IEEE 802.16/802.16j network “tree”protocol wherein a source node must pass its information to nodes onhigher branches which, in turn, distribute the information to lowerbranch nodes until the information reaches the destination node, even ifthe source and the destination nodes are in range and could otherwisecommunicate directly with one another.

U.S. patent application Ser. No. 11/998,356 filed Nov. 29, 2007, andassigned to the assignee of the present application and invention,discloses a process and system for enhancing connectivity among nodes ina wireless network with changing topology, wherein certain nodes areconfigured to change roles by operating in (i) an ad hoc or mesh mode,(ii) a point-to-multipoint mode, or (iii) both modes simultaneously, inorder to maintain optimum connectivity among all nodes of the network.The '356 application was published as US 2009/0141653 on Jun. 4, 2009.

U.S. Pat. Appl'n Pub. No. 2002/0027894 (Mar. 7, 2002) describes ahierarchical network structure having a three tier structure similar tothe existing Internet or phone system, wherein wired links are replacedwith wireless links and the top two tiers are static and pre-configured.A common “multi-radio” approach is implemented wherein IEEE 802.11 isadopted for mesh communications, and IEEE 802.16 is used PMPcommunications. That is, different communications protocols for are usedfor the different tiers. See also, U.S. Pat. Appl'n Pub. No.2006/0083205 (Apr. 20, 2006) which discloses the concept of acoordinated access band (CAB), wherein requests for dynamic access tothe CAB spectrum are mediated and time-bound rights are granted for usein either a cellular or an ad hoc mode.

As far as is known, no one protocol has been proposed that will enablePMP and mesh/MANET communications to occur simultaneously over one ormore shared channels of a wireless network (including networks thatfollow the IEEE 802.16 standard or are WiMAX based), while avoidinginterference between the two modes of communications on a given channelor channels. Note that IEEE 802.11 has a PMP protocol of sort (calledPCF) which is not generally practiced or employed. PCF differs fromother PMP networks such as WiMAX, however, and techniques for using PCFin IEEE 802.11 networks cannot be applied in other PMP networks.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a method of allowing membernodes of a wireless point-to-multipoint (PMP) network to participate inmobile ad hoc (MANET) or mesh communications with other nodes on ashared set of channels without interfering with network communicationsexchanged using a PMP protocol, includes transmitting a downlink signalfrom a base station node to a number of subscriber station nodes in aPMP network, defining a downlink map in the downlink signal forscheduling first time periods for transmitting messages from the basestation node to corresponding ones of the subscriber station nodes, anddefining an uplink map in the downlink signal for scheduling second timeperiods for allowing a subscriber station node to transmit messages tothe base station node in a scheduled second time period. In addition,the method includes allocating a MANET/mesh zone in either one or bothof the downlink and the uplink maps, each zone operating to reserve oneor more time slots and channels in which nodes using a MANET or meshprotocol, including the base and any of the subscriber station nodes,can communicate with other nodes using the MANET or mesh protocol andavoid interfering with network communications between the base and thesubscriber station nodes under the PMP protocol.

For a better understanding of the invention, reference is made to thefollowing description taken in conjunction with the accompanying drawingand the appended claims.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing:

FIG. 1 is a block diagram of a typical PMP network topology;

FIG. 2 shows a typical MANET network topology;

FIG. 3 illustrates a typical PMP signaling frame structure;

FIG. 4 illustrates a typical IEEE 802.16d standards-based mesh signalingframe structure;

FIG. 5 shows a typical unifying slot assignment protocol (USAP) basedMANET signaling frame structure;

FIG. 6 shows a PMP frame structure that incorporates MANET or mesh zonesaccording to the invention;

FIG. 7 illustrates a PMP compatible MANET frame structure according tothe invention;

FIG. 8 shows a PMP compatible USAP frame structure according to theinvention;

FIG. 9 illustrates a PMP compatible mesh frame structure according tothe invention;

FIG. 10 illustrates the IEEE 802.11 access protocols;

FIG. 11 shows an IEEE 802.11 standards-based MANET compatible PMP framestructure according to the invention;

FIG. 12 shows a combined IEEE 802.16 and IEEE 802.11 standards-basedframe structure according to the invention;

FIG. 13 is a functional block diagram of a multi-protocol networkstation or node, according to the invention;

FIG. 14 shows a PMP compatible META-MANET frame structure according tothe invention;

FIG. 15 shows a hybrid PMP/MANET network topology according to theinvention;

FIG. 16 is a block diagram of apparatus capable of functioning as amulti-protocol network node according to the invention; and

FIG. 17 is a functional block diagram of a multi-protocol network nodeaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, a “mesh point” (MP) is any node that is a member of anetwork and practices either MANET or mesh signaling protocols that areestablished for the network. According to the invention, the MP nodesmay coexist as well as communicate with other member nodes of thenetwork that practice PMP signaling protocols. The PMP protocols aredefined herein in three protocol functionality suites, namely; BaseStation (BS), Fixed Subscriber Station (SS), and Mobile SubscriberStation (MS). Specifically, coordination is established between the BSand the MP protocol sets. The SS and the MS protocol sets need notinteract with the MP protocol set provided the former sets onlyparticipate in the PMP aspects of the network. It is, however, at timesconvenient as well as advantageous to be able to co-locate the SS or theMS protocols with the MP protocols at the same station or node in orderto implement specific architectural elements.

A “Relay Station” (RS) is defined herein as an element containingspecific subsets of the BS and the MP functionality. Specificarchitectural elements useful for MANET routing and topology control arealso possible. These include, for example, concepts of a domain node(DN), a domain lead node (DL), and a bridge node (BN), as defined in,e.g., U.S. patent application Ser. No. 11/546,783, filed Oct. 12, 2006,titled “Adaptive Message Routing for Mobile Ad Hoc Networks”. The '783application issued as U.S. Pat. No. 7,656,851 on Feb. 2, 2010, and isassigned to the assignee of the present application. All relevantportions of the '851 patent are incorporated by reference.

FIG. 1 is a block diagram illustrating an example embodiment of awireless communication system or network that implements a Point toMulti-Point (PMP) topology. The network may practice one of manyspecific protocols, for example, IEEE 802.16-2004, IEEE 802.16e-2005, orrelated versions of these protocols such as WiMAX or HIPERMAN. Thenetwork of FIG. 1 may operate in, for example, radio frequency bands atapproximately 400 MHZ, 700 MHZ, 2400 MHZ, 3100 MHZ, 4400 MHZ, 4600 MHZ,or 5800 MHZ. Frequencies as high as 60 GHz or more are consideredsuitable for operation of the mentioned PMP protocols. Instantaneouschannel bandwidth may range from less than 1 MHZ to approximately 20MHZ. Bandwidths as high as 500 MHZ or more are feasible. Nodes of thenetwork may employ a wide variety of antennas such as, e.g., omni, fixeddirectional, sectored, beamforming or adaptive. Multiple Input MultipleOutput (MIMO) as well as Multi-User Detection (MUD) networkingtechnologies may also be applied in a known manner. Further, known TimeDivision Duplex (TDD) and Frequency Division Duplex (FDD) technologiesmay be applied as well.

A variety of currently known modulation and Physical Layer (PHY)implementations can also be employed in the network. Common modulationschemes include Orthogonal Frequency Division Multiplexing (OFDM), andOrthogonal Frequency Division Multiple Access (OFDMA). Single Carrier(SC) PHYs may also be used, as well as known spread spectrum techniques.Typical constellations used to modulate the carriers are QuadraturePhase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (16 QAM),and 64 Quadrature Amplitude Modulation (64 QAM). Other known modulationtechniques may be practiced as well. Error Correction Coding (ECC) wellknown in the art such as, e.g., Viterbi, Reed Solomon, Turbo, and LDPCmay also be utilized, possibly in combination with one another.Interleaving may also be applied in a known manner.

PMP networks are distinguishable from other wireless networks withrespect to the organization of nodes in the network. For example, inFIG. 1, Base Station (BS) node 110 maintains a wireless coverage area100 by the use of RE transceivers and one or more antennas. Any of thementioned frequencies, PHYs, modulations, ECC, and constellations (aswell as others) may be used to implement the PMP and other topologiesdescribed herein. A Media Access Controller (MAC) may also be used in aknown manner to determine when various nodes in the FIG. 1 networkshould be either transmitting or listening within the coverage area 100.

A number of fixed Subscriber Station (SS) nodes 120, and a number ofMobile subscriber Stations (MS) nodes 130, may be situated within thecoverage area 100. Those nodes interested in receiving services from BSnode 110, register with the node 110 and form links with the node. TheBS node 110 may be configured to control which nodes receive andtransmit, and in which time intervals, through MAC messages. PMP linksare represented by thin solid lines such as link 140 in FIG. 1. SS node120 and MS node 130 are configured to form links only with the BS node110, and can not form links with one another even though they may bewithin RF communication range, i.e., one hop, of each other. The BS node110 forwards communications (packets or messages) that originate fromand are addressed to those nodes within the coverage area 100 thatdesire to communicate with one another. In addition, the BS node 110provides connectivity for nodes within the coverage area 100 with nodesof other networks via, for example, the Internet. The thick line 150 inFIG. 1 indicates a communication link between the BS node 110 and othernetworks 160. The link 150 may be provided via a wired or a wirelessinterface.

FIG. 2 shows a typical wireless communication network having nodes (MP)configured to operate within a Mobile Ad Hoc Network (MANET) or meshnetwork topology. A MANET network has the property that any of its nodesmay be in motion while communicating with one another. MANET networksare Ad Hoc in that it is not necessary for a central authority (such asthe BS node 110 in FIG. 1) to have sole power to establish and to definethe parameters of links between any two or more of the nodes MP of thenetwork. Any two of the nodes may establish a link with one anotherindependent of other nodes or communication entities in the network. Thelinks may be transient, and they need not be pre-scheduled. In addition,the nodes of the MANET network in FIG. 2 are typically capable ofmaintaining multiple links with other nodes simultaneously.

The term mesh network may have a number of meanings. Typically, a meshnetwork is a special case of a MANET in that at least some of thenetwork nodes MP are assumed to be static, and some amount ofpreplanning or scheduling may be required. In addition, some nodes mayrequire communication with a central authority for the purpose ofregistration with the mesh network. In the present disclosure, the termsMANET and mesh are used interchangeably, with both terms implying themore general MANET unless stated otherwise.

The U.S. Department of Defense has experimented with MANET networks fora number of years. Examples of MANET networks include the WidebandNetworking Waveform (WNW) and the Soldier Radio Waveform (SRW).Commercially, the IEEE 802.11 (or simply “802.11”) waveform is oftenused to experiment with MANET networks since, in one mode of operation,the standard does support a degree of mobility requiring no centralizedauthority. An IEEE 802.11 Task Group (802.11s) is currently working on a“mesh” 802.11 solution that is not intended for mobility, althoughongoing work by an 802.11p group may result in an IEEE 802.11—basedMANET for use in Intelligent Transportation Systems (ITS) applications.IEEE 802.16-2004 included a mesh capability wherein nodes were generallypresumed to be static, and coordination with a centralized authority wasrequired. As mentioned, the earlier defined mesh mode of IEEE 802.16 iscurrently withdrawn.

In general, MANET and mesh networks incorporate the same types of symbolconstellations, PHY layers, modulations, ECC, interleaving, duplexingtechniques, MIMO and MUD techniques, antenna types, frequency bands, andbandwidths as are used by PMP systems. MANET/mesh networks differ fromPMP networks primarily in the configurations of their medium accesscontrol (MAC) and networking layers.

In FIG. 2, the nodes that practice MANET or mesh protocols are termedmesh Point (MP) nodes. FIG. 2 shows a wireless coverage area 200containing three nodes MP 210, 220, 230 which are within communicationrange of one another. Links formed among the nodes using MANET or meshprotocols are shown in dashed lines such as at 260.

Terms familiar to those skilled in the art include “one hop” and “twohop” neighbors. In FIG. 2, node MP 240 is a one hop neighbor of node MP230 in that a single RF transmission is sufficient to communicate ineither direction between the nodes MP 240 and MP 230. Node MP 240 is atwo hop neighbor of node MP 210 in that a packet or message must undergotwo RF transmissions to complete a path (via node MP 230) between thenodes MP 240 and MP 210.

For this example the three nodes MP 210, 220 and 230 are fully connectedin that any one of them can link directly with the other two. Thewireless coverage area (200) is representative of this connectivity.Another wireless coverage area 250 contains nodes MP 230 and 240 whichcan also link directly with each other, although node MP 240 cannotdirectly link with either one of the nodes MP 210 or 220. Thus, at thelink level, the four nodes MP 210, 220, 230, and 240 are not fullyconnected with one another. MP nodes do, however, have an ability toforward network traffic from one link onto another link. For example, inFIG. 2, node MP 230 can forward traffic from its link with node MP 240,onto its links with either one of the nodes MP 210 or 220, and viceversa. This typically occurs at the network layer but may also takeplace at the MAC layer, as is known in the art. Thus, the node MP 240can communicate in either direction with nodes MP 210 and 220, albeitthrough an intermediate node.

FIG. 15 is a block diagram of one embodiment of a wireless communicationsystem or network implementing a hybrid PMP/MANET network topology,according to the invention. Four wireless coverage areas 1500, 1505,1510, and 1515 are shown, wherein each node in a given coverage area iswithin RF communication range (i.e., one hop) of every other node in thegiven coverage area. Some nodes are identified as purely PMP elements,i.e., as being either an SS or an MS node. Other nodes are identified aspurely MANET/mesh (MP) nodes.

A new set of nodes, each of which is constructed and arranged topractice multiple protocol sets according to the invention, are alsoshown in FIG. 15. For example, node 1520 is labeled BS/MP because it isconfigured to operate under a BS PMP protocol set and an MP protocolset. Node 1525 is labeled MS/MP because it is arranged to operate underan MS PMP protocol set and an MP protocol set. Node 1530 is labeledSS/MP because it is capable of operating under an SS PMP protocol setand an MP protocol set. Links formed between nodes using the PMPprotocol set are shown as solid lines in FIG. 15, and links formed usingthe MP protocol set are shown as dashed lines. Any given node isequipped to establish a link with any of the other nodes of the network.

A set of heuristics may be employed to determine which protocol set (PMPor MANET/mesh) to use for a given link. An example set of heuristicswould be as follows: BS, SS, and MS nodes exclusively use the PMPprotocols. MP nodes exclusively use the MANET/mesh protocols. If a nodeis a BS/MP, it always accepts links from and serves MS, SS, MS/MP andSS/MP stations using the PMP protocols. A BS/MP always links to otherBS/MP using the MANET/Mesh protocols. If an MS/MP or SS/MP is in rangeof a BS or BS/MP, it links with those nodes using PMP protocols. If anMS/MP or SS/MP is not in range of a BS or BS/MP, it links to otherstations using the MANET/Mesh protocols. MS/MP, SS/MP, and MP stationsnever refuse a link from MS/MP, SS/MP and MP which cannot communicatedirectly with a BS or BS/MP. Other more complicated sets of heuristicsare possible. Such heuristics might include the ability of nodes tochange roles, for example, from an MS/MP to a BS/MP, and vice versa. Seethe earlier mentioned published application US 2009/0141653.

In the network of FIG. 15, both PMP and MANET topologies are subsumedinto a hybrid PMP/MANET topology for the network. The techniquesdescribed herein may also be applied in networks or systems that sharemultiple RF channels, for example, OFDMA. To facilitate an understandingof the invention, the signaling frame structures currently used in PMP,mesh and MANET network protocols, are explained first below.

FIG. 3 shows a typical PMP frame structure that is used in a TDD systemwith OFDMA modulation, but analogies for FDD and the other modulationstypes identified (particularly for OFDM and single carrier) are known tothose skilled in the art. Further details of the PMP frame structure ofFIG. 3 may be found in the IEEE 802.16-2004 and 802.16e-2005 standardswhich are incorporated by reference.

A PMP frame is comprised of many RF “bursts”. A Downlink Subframe 325includes a set of bursts all of which originate at a BS node and aredestined for one or more SS or MS nodes previously registered with theBS node. Some of the bursts have special purposes. For example, thePreamble 300 indicates the start of the frame and also facilitates timeand frequency synchronization within the network. Other key bursts mayinclude a Frame Control Header (FCH) 305 which details key PHYproperties that are needed to interpret other RF bursts in the frame, aDown Link (DL) MAP 310 which details where the various DL bursts arelocated within the frame, and an Up Link (UL) MAP 315 which detailswhere various UL bursts are to be located. The BS node defines andgenerates all the mentioned bursts at the beginning of each frame. Afterthese initial bursts, a series of DL data bursts such as DL Burst #1 320are provided as scheduled in the DL MAP 310.

The Downlink Subframe 325 is followed (for TDD systems) by aTransmit/Receive Transmission Gap (TTG) 330 during which there are nointentional transmissions. This time period allows for SS nodes in thenetwork to switch from a receive to a transmit mode, and for the BS nodeto switch from a transmit to a receive mode of operation. An UplinkSubframe 335 then follows the TTG 330. The subframe 335 includes burstsfrom one or more SS or MS nodes all of which bursts are destined to theBS node. Several of the burst allocations may also have specialpurposes. These include ACK-CH 340, Ranging 345, and Fast Feedback(CQICH) 350 the functions of which are known to those skilled in the artand defined in the IEEE 802.16-2004 and 802.16e-2005 standards. Inaddition, Uplink data bursts such as UL Burst #1 355 may occur. Asmentioned, the positions of all Uplink traffic are defined by the UL MAP315 transmitted from the BS node during the Downlink Subframe 325.Finally, a Receive/Transmit Transmission Gap (RTG) 360 may be providedto allow the network stations again to switch their receive/transmitmodes.

The scheduling of the bursts is an important consideration in a PMPnetwork. This is accomplished by using “slots”. In a most general case,a slot is a “tile” whose dimensions correspond to the smallest number ofmodulation symbol periods that can be scheduled, by the smallest numberof logical subchannels that can be scheduled. The subchannels roughlycorrespond to frequency groups; but because of the particularmodulation/coding techniques implemented in the network, adjacentlogical channels may not always correspond to physically adjacentfrequencies.

FIG. 3 shows slotting based on OFDMA symbols. When the smallest numberof logical channels that can be allocated into a slot equals all of theavailable logical subchannels, then the OFDMA topology degenerates intoOFDM. If in fact only one logical channel is available and the channelcontains a single frequency, the modulation scheme degenerates intosingle carrier.

The minimum number of logical subchannels in a slot and the minimumnumber of modulation symbols in a slot, may differ in the UplinkSubframe 335 from that which exists in the Downlink Subframe 325. Also,while the total number of modulations symbols in a frame may be welldefined, the partitioning between uplink and downlink phases for TDDsystems is not. That is, the timing of the TTG 330 can change dependingon current needs of the system. Thus, varying numbers of modulationsymbols may occur in each subframe of a given frame. Further, the TTGand the RTG gaps 330, 360 need not be multiples of the modulation symboltime. Modulation symbols in the Uplink Subframe 335 may not align with aconstant time base triggering off the start of each frame. The TTG 330may, or may not, be in a fixed location for every PMP frame depending onthe specific implementation.

FIG. 4 shows a typical mesh frame structure based on the original IEEE802.16-2004 (802.16d) standard and known to those skilled in the art.Frame Boundaries 400 are indicated, and the length of the frame isconfigurable. The frame is divided into a number of subframes, the firstof which is a Network Control Subframe 405. Details of the Subframe 405are shown at the lower left in the figure, wherein the subframe 405 isdivided into transmit opportunities the first of which is for NetworkEntry messages 410. A number of transmit opportunities for NetworkConfiguration messages 415 are also provided. The number of transmitopportunities in the Network Control Subframe 405 is a networkparameter. A Data Subframe 420 follows the Network Control Subframe 405.The number of Data Subframes 420 is also a network parameter.

Each Data Subframe 420 contains a relatively large number of minislots425. The minislots 425 are each smaller than a complete message butallow for a great deal of scheduling granularity and efficiency. Betweenthe Data Subframes 420 are Schedule Control Subframes 430. The structureof a Schedule Control Subfame 430 is shown at the bottom right of FIG.4. The Subframe 430 includes a number of Schedule Control TransmitOpportunities 435 for Schedule Control Messages. Two basic types ofscheduling are supported, namely; Centralized 435, and CoordinatedDistributed 440. The total number of Schedule Control transmitopportunities, and the split between the Centralized and the CoordinatedDistributed transmit opportunities 435, 440, are network and systemparameters. In addition, Uncoordinated Distributed Schedule Controlmessages 445 may be contained within a Data Subframe 420.

FIG. 5 is an example MANET frame structure based on a protocol known inthe art as Unifying Slot Assignment Protocol (USAP), and described by C.David Young in “USAP Multiple Broadcast Access: Transmitter- andReceiver-Directed Dynamic Resource Allocation for Mobile, Multihop,Multichannel, Wireless Networking”, IEEE MILCOM 2000, at pages 549-53. ASuperframe 500 includes a number of successive frames. Components in allof the frames are similar, but their usage varies and repeats after agiven number of frames. For example, components in frame 505 (1^(st)frame) are shown, including a set of network control slots 510. Thecontrol slots 510 are of a fixed size so as to allow a single networkcontrol message to be transmitted from a single node in each such slot.Different means may be used to allocate the control slots among thenetwork nodes, as described in the USAP protocol and known to thoseskilled in the art. A separate set of fixed size slots are reserved forBroadcast Data 515. The slots 515 are allocated for users according tothe USAP protocol using means known to those skilled in the art. Thesize of the Broadcast Data slots 515 may differ from the size of theNetwork Control Slots 510.

A separate set of fixed size slots are defined as Unicast Data Slots520. The Unicast Data Slots 520 may also be used for Broadcast Data. Theslots 520 are allocated for users according to the USAP protocol bymeans known to those skilled in the art. The USAP protocol operatesacross multiple frequency channels 525. Slots are allocated across thechannels according to the protocol and means known to those skilled inthe art.

FIG. 10 represents a typical media access scheme as described, forexample, in IEEE 802.11-1999 (“802.11”). No formal frame is defined in802.11; however, a Target Beacon Transmit Time (TBTT) interval 1000 andother associated 802.11 constructs that are multiples of the TBTT 1000can be used as a Start of Frame reference. Note that the meaning of theword “frame” in the IEEE 802.11 standard is roughly equivalent to theterm “message” as used in the present disclosure. The 802.11 protocolrequires that a Beacon message 1015 be transmitted approximately at atime corresponding with the TBTT 1000. How this is accomplished dependson the particular coordination function that is active when the TBTT1000 occurs.

Two coordination functions are defined within IEEE 802.11, namely; theDistributed Coordination Function (DCF) and the Point CoordinationFunction (PCF). The DCF is used during an 802.11 Contention Period (CP)1055. The PCF is used during an 802.11 Contention Free Period (CFP)1050. If the TBTT 1000 occurs during the CP 1055, then a BeaconContention phase 1040 begins. The Beacon Contention 1040 allows allAccess Point (AP) or Independent Basic Service Set (IBSS) participantsto send Beacons. If any traffic currently exists on the channel as at1005, then all stations defer until the channel clears. Once the channelclears, contending stations defer for a DCF Inter-Frame Space (DIFS)time 1035. Then, each station defers by a random number of contentionslots 1070. AP stations or nodes will always send their Beacons and willcontinue the deferral process until each station is allowed to transmit.In an IBSS, all stations participate and take turns transmitting theBeacon. Each station defers by a random time, and the station with theshortest deferral time is allowed to transmit. Once a Beacon issuccessfully transmitted, stations in the IBSS do not attempt to send abeacon again until the next TBTT 1000 in a CP.

AP nodes implementing a CFP under the PCF follow a different beaconingprocedure. An AP node defers to DCF traffic as before, and then waits aPCF Inter-Frame Space (PIFS) time 1010. No Beacon Contention isrequired, however, and a Beacon Message 1015 is transmitted immediately.The PIFS is shorter than a DIFS, thus ensuring that the PCF Beacon isfavored over other Beacons.

FIG. 10 also illustrates access techniques practiced under 802.11. MANETnetworks are often built around the DCF function in 802.11. See, e.g.,R. J. Hall, et al., “A Tiered Geocast Protocol For Long Range Mobile AdHoc Networking”, MILCOM 2006; and J. P. Hauser, et al., “Mobility andRouting Protocols For 802.11 Extended Service Sets”, U.S. Naval ResearchLaboratory MILCOM 2003, at pages 1036-41. Under the DCF, each station ornode decides when it should transmit based purely on local informationsuch as the media state and local state machines. An example DCFtransmission which could be used for MANET communications is shown inthe figure as DCF Tx 1036.

FIG. 10 further shows some details of PCF communications as may berelevant to the present invention. Communications using the CFP arecoordinated by an AP node acting as a central control station. Duringthe CFP, other nodes associated with the AP node may only transmitmessages if polled by the AP node. PCF Poll 1020 and Response messages1025 are shown in the figure. The length of the CFP, and which TBTT areassociated with the CFP, are predefined by the AP node and advertised inthe PCF Beacon messages. A node that hears the PCF Beacon knows thestart of all the CFP and the Advertised End of each CFP 1060. If an APnode decides that no further PCF communications are necessary prior tothe advertised end of the CFP, it can cause the Actual end of the CFP1065 to occur early by transmitting an 802.11 CF-END message 1030. Thispermits DCF messages to take advantage of time that would otherwise beleft open.

As mentioned, the present invention enables PMP systems and MANET ormesh systems to interoperate with one another on a given network channelor channels. Accordingly, critical frame components of PMP and ofMANET/mesh frame structures are mapped into a common frame structure, byretaining critical components of both protocols and reserving air timewithin the frame structure for operational needs of either protocol.

FIG. 6 illustrates a PMP frame structure that is modified to incorporateMANET Zones according to one embodiment of the invention. Variableparameters identified previously for PMP networks, for example, types ofconstellations, PHY, modulations, duplexing techniques, MIMO/MUDtechniques, antenna types, frequency bands, and bandwidths of operation,may all apply to the PMP/MANET frame structure of FIG. 6. A preferredembodiment may, however, adaptively select between QPSK, 16-QAM and64-QAM modulations based the available Signal to Interference plus NoiseRatio (SINR), use OFDMA PHY modulation for the PMP traffic (as definedin the 802.16-2004 and 802.16e-2005 standards), employ a combination ofViterbi and Reed Solomon ECC with interleaving as defined in thestandards, use a time division duplex (TDD) transmission scheme, operateat around 400 MHZ without MIMO, use omni antennas, and have a 20 MHZBandwidth. Further, it may be preferable to use a MAC as defined in theIEEE 802.16 standards and modified as described herein to coexist withMANET protocols.

In the PMP frame structure shown in FIG. 6, the frame size may vary fromabout one millisecond to one second, with about five milliseconds beingpreferred. In FIG. 6, a Superframe 600 has N frames. N would normally befixed, but could be variable depending upon a specific MANET protocolselected for implementation. Integers between 1 and 1024 are examples ofacceptable values, although larger values are within the scope of theinvention. A preferred embodiment would use, for example, N=200. Keyaspects of the PMP frame of FIG. 3 are preserved, and the labeling ofthose aspects is also preserved.

In the structure of FIG. 6, reserved portions are introduced in theframe, some of which are labeled as mesh or MANET Zones (MZ). Accordingto the invention, PMP BS nodes may also operate as MP nodes and thusmust be fully aware of the MANET/mesh frame timing and schedulingestablished for the network. The scheduling entity that defines the PMPframe format must therefore account for time periods used by the MANETprotocols as the MANET Zones, and ensure that no scheduling conflictwill arise between MANET traffic and PMP traffic. The MANET zones arescheduled in the DL MAP 310 and the UL MAP 315 in FIG. 6 using reservedcodes or other means to indicate that the zones are not available forPMP use. Heuristics known to persons skilled in the art may be employedto ensure that MANET traffic will not prevent proper operation of thePMP network.

For example, a MANET scheduler may be configured so that not more than50% of the PMP frame is ever used for MANET constructs, thereby ensuringthat at least as much time is available for PMP constructs. Smallervalues, e.g., 5% or 10% are also possible as well as larger values(e.g., 90%). The MANET zones may encompass all network frequencychannels during a determined time slice as in MZ #1 605 and MZ #2 610,or occupy only a portion of the logical frequency band as in MZ #3 615.The MZ may occur in the downlink portion of the PMP frame as for MZ #1605, or in the uplink portion as for MZ #2 610. In a preferredembodiment, the MZ would correspond to sets of Uplink or Downlinkscheduling time slots as appropriate. It is also preferred that the PMPscheduler be aware of other MP nodes operating as SS nodes or MS nodeson the PMP system, and ensure that the MZ includes adequate time tochange transmission modes (receive or transmit) based on traffic beingreceived by the MS or SS nodes operating in the MANET/mesh network. Someportions of the frame time are preferably always reserved for MANET/meshoperation. This would support network control transmissions for theMANET network, but may also include dedicated time for MANET datatransmission. The amount of time reserved would then become a PMPnetwork parameter.

FIG. 7 illustrates a MANET frame structure that is compatible with a PMPoperating protocol according to the invention. All of the mentionedsystem parameters that may be selected for a typical PMP network,including types of constellations, PHY, modulations, duplexingtechniques, MIMO/MUD techniques, antenna types, frequency bands, andbandwidths of operation, may be applied in the MANET/mesh networksdisclosed herein. Preferably, the same values of these parameters asgiven for the PMP network in FIG. 6, apply to a network operating withthe frame structure of FIG. 7 but for certain exceptions noted below.

FIG. 7 shows the same Superframe structure 600 as shown in FIG. 6. Thesame frame (identical PMP frame structures and same frame index) as inFIG. 6 is considered. Accordingly, while the field structures and dataindicated in the frame in FIG. 6 are not labeled as such in the frame ofFIG. 7, they may in fact be fully presented in the reserved orunallocated portions of the MANET frame of FIG. 7. It is assumed thatthe MANET scheduling is based on time slot sizes that differ from thoseused by the PMP nodes in the network. Also assume that the MANET keepstrack of its schedule based on a modulation symbol index 700 withrespect to the start of the frame, and that the MANET nodes use OFDMAmodulation symbols for data in the frame structure of FIG. 7.

A preferred embodiment maintains the symbol index and time slots basedon the use of OFMDA modulation symbols, but would advantageously switchmodulations during the ML Bursts and the MANET Control Subframe 705. Forexample, if a 2048 tone OFMDA modulation is used for data, switching toa 256 tone OFDM of the same bandwidth may be advantageous during theMANET Control Subframe 705 in that the symbols are of shorter duration.As indicated by the doted lines, eight OFDM symbols may fit in the sametime interval as one OFDMA symbol with a little room to spare. The useof OFDM symbols makes allocations of transmit and receive turnaroundgaps easier for short broadcast messages which may include Controlmessages.

If multiple nodes transmit broadcast messages in an OFDMA framesimultaneously but at different frequencies, they would be unable tohear one another since they cannot transmit and receive at the same timeduring a given OFMDA symbol. This defeats the purpose of broadcastmessages, so using symbols that are shorter in time wherein each timeslice is occupied by a single user, has advantages. Other schedulingslot structures may also be employed, and the timing reference point maybe at the start of the entire Superframe rather than at the start ofeach frame.

A PMP reserved section 715 is provided in the MANET Data Subfame 710 toensure that no MANET traffic will interfere with critical PMP fields atthe beginning of the subframe 710. This minimally covers (from FIG. 6)the structures 300, 305, 310, and 315, and may also cover some portionof the data in the PMP Downlink Subframe. The exact portion of thesubframe 710 that is reserved is set as a MANET Network parameter. MANETLink (ML) bursts are defined based on time and logical (frequency)channel “slots” similar to those used in USAP. The percentage of theframe that can be occupied by MANET traffic may be set as a MANETnetwork parameter, and preferably is not more than 50%. ML bursts may belimited to a subset of the total number of channels available in thesame way they are limited in the PMP network, and in the USAP framestructure (FIG. 5). An example of this is ML Burst #3 720 in FIG. 7. Thesame mechanisms used to allocate USAP traffic across frequency channelsmay be used for the frame structure in FIG. 7, as will be apparent topersons skilled in the art. The logical subchannels in FIG. 7 may besubstituted for the frequency channels 525 used in FIG. 5.

As noted, simultaneous transmissions in an OFMDA frame format may beproblematic. The applicable slot assignment algorithm must employ aheuristic to ensure that nodes of the network do not transmit in OFDMAsymbols when the intended receiving node is transmitting in a differentlogical channel of the same OFDMA symbol. Such a heuristic may not evenbe sufficient because some time is required to switch from transmit toreceive. Thus, if the intended receiving node was transmitting in thesymbol before, or needs to transmit in the symbol after, then a gap ofsome sort may need to be inserted in the transmissions. This is true forOFDM and SC as well as OFDMA.

In FIG. 7, MANET Link Gaps (MLG) 725 are strategically placedimmediately before and after each of the ML Bursts. The MLG 725 are onesymbol wide, but may be shorter, for example, one-half symbol widebefore and after the actual burst. Because OFDM and OFDMA symbols ofteninclude a cyclic prefix, it may not be necessary to include the MLG 725.Thus, the gaps are considered optional and their inclusion will dependon modulation, propagation, and other system parameters. In addition tothe front portion of the frame, it may be desirable to reserve otherportions of the frame to avoid conflicts with other PMP functions suchas, e.g., ranging or Fast Feedback. Such reservations may be consideredoptional.

FIG. 8 depicts a PMP compatible USAP frame structure according to theinvention. For example, a 20 MHZ wide channel with 2048 OFMDA tones isused for the PHY. The frame is five milliseconds long, and thesuperframe 600 is of one second duration. USAP allocation mechanismsknown in the art are used to define unicast aand broadcast datatransmissions. A subcycle occurs every 125 msec (every 25 frames), andcorresponds to a USAP “frame”. Each frame has up to eight ML bursts allof which occur during the same nine OFMDA symbols but in differentlogical sub-channels. Depending on the coding scheme, there may be sparelogical channels within the nine OFMDA symbols used. For example, ifthere are 70 logical subchannels and eight logical subchannels per MLburst, then six logical subchannels are unused. The unused subchannelsmay be grouped together, or used to provide logical channel gaps betweenthe ML bursts. The eight ML bursts correspond to eight frequencies inthe USAP protocol. In 25 frames on a single logical channel, there are25 “Slots” in a subcycle. The first slot, and every fifth slotthereafter, are “broadcast” slots. The other 20 slots play the same roleas the “reservation/standby” slots in the USAP protocol.

PMP networks treat the last four symbols of the 48 symbol frames asreserved for the MANET Control Subframe. OFDMA modulation symbols areused in the MANET Control Subframe. Three symbols are used to implement“bootstrap” slots. This provides 20 sets of bootstrap slots persubcycle. Because they are broadcast, however, it is expected that onlythe lowest numbered bootstrap slots would be used in each frame. Slotsthat occupy adjacent Logical Sub-Channels of the same OFMDA symbol setcould be aggregated into larger slots for more signaling capacity, ifneeded.

These numbers correspond to more slots in all regards than called for inthe basic USAP frame format. Extra slots can simply be truncated and theexact USAP algorithm implemented. One skilled in the art may, however,extend the basic USAP protocol for greater performance by takingadvantage of the additional capabilities.

In all, 15 out of 48 symbols are allowed for use in following the MANETprotocol. The ML Burst size may be adjusted to increase the capacity, orto add more slots and increase control capacity. Also, the ML bursts areindicated as starting after the J^(th) symbol. a preferred embodimentwould, however, group the ML bursts adjacent with the MANET ControlSubframe, and thereby force J to a value of 33.

Unallocated air time is used by the PMP components of the network. Also,since a PMP BS node listens to the signaling in the MANET component ofthe network, the BS node can allocate MANET slots that are not in activeuse to PMP users on a temporary basis. IEEE 802.16 uses differentpermutation zones depending on how the PHY is configured during aparticular area in a PMP frame. Preferably, all of the MANET/mesh nodesuse the same permutation zone setting for their MANET communications.

FIG. 9 depicts a PMP compatible mesh frame structure based on the meshnetwork defined in IEEE 802.16-2004, according to the invention. Again,the structure contemplates a 20 MHZ bandwidth and a five millisecond PMPframe length. The PMP communications are assumed to be OFDMA, and allmesh communications (Data and Control) are assumed to be OFDM. The meshminislots 425 in the mesh frame structure of FIG. 4, are preferably setequal to the OFDMA symbol time which is assumed to be about 8.2 timesthe OFDM symbol time. The exact amount depends on the modulationparameters selected. The use of an OFDMA symbol as a minislot deviatesfrom the standard convention of defining minislots as multiples of theunderlying PHY modulation (OFDM for mesh communications). From atransmission scheduling perspective, however, all that matters is thatthe exact time at which transmissions start, is known. The use of OFDMAsymbol times as minislots is therefore easily accommodated. The MLGdescribed earlier still exist, but are comprised of a single OFDM symboleach. In FIG. 9, MLG are confined within the mesh minislots and arerepresented in darkened bands 900.

In the illustrated embodiment, the number of minislots per frame isrestricted to 32 (out of 48 symbols total). The first four symbols ofthe frame are reserved at 815 for PMP protocol communications in thenetwork. The parameters for the mesh Control Subframe are selected sothat five Transmit Opportunities are provided every Control Subframe,each consisting of seven OFDM symbols. This means that five OFDMAsymbols must be reserved for the mesh Control Subframe.

The first Transmit Opportunity is timed relative to the start of thetime reserved for the mesh Control Subframe. A subcycle of four frames(20 milliseconds) exists within the mesh Superframe which is one secondlong. Starting with the first mesh frame of the Superframe, the meshControl Subframe of every fourth mesh frame is dedicated for the NetworkControl Subframe function shown in FIG. 4 at 405. At all other times,the mesh Control Subframe performs the Schedule Control subframefunction depicted in FIG. 4 at 430. Because all unallocated meshcapacity is allotted back to a PMP function, uncoordinated distributedcontrol function messaging is not supported in the frame structure ofFIG. 9. Such messaging could, however, be supported if OFDMA symbols arededicated for that function.

As noted earlier, IEEE 802.11 can provide a basis for a MANET or meshprotocol. In accordance with the invention, it may be convenient to use802.11 constructs for some or all aspects of a mesh or MANET frame thatis capable of sharing a channel with 802.16 PMP traffic. For example, inthe frame structure shown in FIG. 7, IEEE 802.11 DCF protocols may beused to carry control traffic in MANET Control Subframe 705. In such acase, the mesh Schedule and Network Control messages would betransmitted as data messages over 802.11. Also, an 802.11 PHY may beused just in this Subframe, instead of an 802.16 PHY. Moreover, oneskilled in the art could substitute the basic 802.16 OFDM modulation for802.11 OFDM modulation, and thus simplify the modulator/demodulatorrequirements. Data traffic would still travel in ML bursts using theOFDMA or OFDM modulations specified by 802.16. Yet another alternativewould be to use the 802.11 protocols to carry not just mesh or MANETcontrol traffic, but the MANET data as well.

FIG. 11 illustrates an 802.11 MANET Compatible PMP Frame Structure thatmay be implemented in a case where 802.11 constructs are used to carryboth control signaling and data for mesh or MANET, in a MANET subframe1105. Again, either an IEEE 802.11 or 802.16 PHY could operate in theMANET subframe. All 802.16 PMP traffic would be constrained to existwithin a PMP subframe 1115. IEEE 802.16 SS and MS nodes practicing PMPprotocols only, need not be aware of the 802.11 infrastructure. While an802.16 BS node would not need to interpret any 802.11 traffic, it mustat least be aware of the start and end times of the MANET subframe 1105so it may schedule PMP traffic in such a way as not to interfere withthe MANET subframe 1105. Ideally, the BS node should be capable ofpracticing both the 802.16 and the 802.11 protocols so that it canbridge traffic between those MANET and PMP nodes that are not equippedto practice both protocols, and help control the MANET nodes practicing802.11 protocols so that the MANET nodes do not interfere with the PMPnodes.

FIG. 12 shows a combined IEEE 802.11/802.16 frame structure which allows802.11 and 802.16 nodes to share the same media. It assumessynchronization between the 802.11 (MANET) infrastructure and the 802.16(PMP) infrastructure. Such synchronization may, for example, be providedby a BS node that practices both the 802.11 and the 802.16 protocols, orby having a common timing reference for the infrastuctures as may beprovided in a known manner using, for example, Global PositioningSatellites (GPS).

In FIG. 12, aspects of the 802.11 protocol are used to prevent 802.11nodes from interfering with nodes that practice the 802.16 protocol. Asnoted previously, TBTT can be used as a nominal Start of Frame for the802.11 infrastructure. Such an 802.11 ‘Frame’ is shown at 1200. An802.16 Frame 1205 is offset from the start of the 802.11 Frame by enoughtime to allow for a fixed amount of Beacon contention 1210 and for aBeacon message 1215. The Beacon may contain the 802.11 CFP parameterssuch that a CFP 1220 is defined that prevents 802.11 nodes fromtransmitting without first being polled by an AP node. The 802.11 nodeswould, however, be configured so as not to poll any stations during theCFP. This ensures that no 802.11 communications will occur during theCFP.

An 802.16 BS node may be configured so as to use a frame that isidentical in length to the time between the starts of 802.11 CFP (mostlikely the time between two TBTT); however the 802.16 BS node controlsPMP communications so that all required PMP communications are completedduring what would be the 802.11 CFP. Thus, 802.16 PMP communicationswill not be interfered by 802.11 communications. Since the 802.16 BSnode controls associated nodes so as to communicate only during the802.11 CFP, no 802.16 communications will occur during the 802.11 CP1225.

In FIG. 12, details of the 802.16 frame structure are simplified, butthe detailed frame structures presented earlier may still be present aswill be understood by persons skilled in the art. Essentially, the802.16 PMP protocol has been substituted for the 802.11 PCF, while the802.11 DCF functions normally. The 802.16 PMP and the 802.11 DCF coexistwithout interfering with one other, and the 802.11 DCF may be used toimplement a MANET as is known in the art.

FIG. 16 is a schematic block diagram of apparatus that may be used topractice the present invention. Other hardware sets may also apply, andFIG. 16 is not intended to limit the scope of the invention. FIG. 16shows three component layers; a General Purpose Process (GPP) layer1600, a Signal Processor (SP) layer 1605, and a Radio Frequency (RF)hardware layer 1610. The GPP layer includes components typically used toconstruct a computer such as a CPU, Memory, and Interface logic. TheInterface logic may be used to implement well known interfaces such asEthernet. The SP layer includes components such as Digital SignalProcessors (DSP), Field Programmable Gate Arrays (FPGA), Analog toDigital Converters (ND), and Digital to Analog Converters (D/A). The RFlayer comprises devices including, e.g., analog integrated circuits(IC), resistors, capacitors, and such other devices as required toconvert the signal provided by the signal processor to a correspondingRF signal. A hardware set having elements that are configured toimplement the required functions is, for example, a Model R3T-P-700radio available from BAE Systems—Network Systems (NS).

FIG. 17 is a functional block diagram of a multi-protocol node that isconstructed using a hardware set such as illustrated in FIG. 16,according to the invention. Data 1700 is communicated to and from themulti-protocol (communications) node from devices that requirecommunications services. The data 1700 may, for example, be passed overan Ethernet interface. Control status information 1705 may also beprovided from external inputs (possibly over the same interface as theData) to determine network configuration parameters. This informationmay also be hard coded into the GPP. A Timing Reference 1710 is passedto the node of FIG. 17 via an interface into the signal processing layerSP. While timing information may also be communicated over the wirelessnetwork, or through the control interface, it is often convenient tohave a dedicated hardware interface that is most easily supported at theSP layer. The timing reference can then be made available to otherlayers and components as, needed.

A networking component 1715 is configured for processing data to betransported by the node of FIG. 17, and is responsible for properlyrouting the data, for example, deciding whether or not the data needs tobe routed over either a PMP link or a MANET link. The control inputs areshown as flowing into the networking component 1715. From there they aredistributed to other components as required. The control inputs may alsobe distributed directly to the other components.

A PMP MAC component 1720 is configured in the node of FIG. 17 toimplement the protocols required for PMP communications. This componentmay implement the protocols for a fixed subscriber node, a mobilesubscriber node, or a base station node depending on the desiredconfiguration. A MANET MAC component 1725 is provided as well. Thecomponent 1725 implements protocols required for the MANETcommunications. It is contemplated that the MANET and the PMP components1725, 1720 are constructed and arranged to interface with one another soas to pass scheduling information 1730 between them. It may, however, bepossible to avoid this scheduling interface by hard coding of schedulinginformation. In addition, a bridging component 1735 may optionally theprovided between the MANET and the PMP MACs 1725, 1720. The bridgingcomponent may be used to pass data between the two protocol sets (PMPand MANET). This allows nodes using the MANET protocol sets tocommunicate with other nodes which might only be using the PMP protocolssets. Some systems may prefer to rely on the routing capability in thenetworking component 1715 to accomplish the same capability as bridging,and omit the bridging component 1735 at the expense of additionaloverhead and delay associated with the networking component 1715.

The Networking, the MAC, and the bridging components may be implementedin a known manner on a general-purpose processor. These components (orparts thereof) may also be implemented via firmware in the SP part ofthe node. Physical (PHY) layer components are normally implemented inthe SP portion of a node, including modulation, error correction coding,interleaving, and any specialized processing such as antenna pattern,equalization, pre-distortion and the like typically employed in modemarchitectures.

The node of FIG. 17 has two PHY components, viz., PHY1 1735 and PHY21740. PHY1 is associated with the MANET protocols, and PHY2 isassociated with the PMP protocols, although a common PHY may be used tosupport both protocol sets. While a common RF component 1745 is providedto support all analog and RF processing required to create theappropriate RF signals (sometimes called “signals in space” or SIS), itmay be convenient to have separate RF components and associated antennas1750 for each protocol set (PMP and MANET). Multiple RF sections andprotocols (such as for MIMO or adaptive antenna implementations) mayeven be necessary for some applications. Also, a PMP Base Station maysupport multiple sectors, each with their own MAC, PHY and RF within thesame node.

FIG. 13 is a functional block diagram of a multi-protocol station or anode practicing specifically the IEEE 802.16 and 802.11 protocols.Details of the networking component are omitted. As will be apparent tothose skilled in the art, there are a number of ways to implement eachof the various functions. For example, separate microprocessors could beused to implement the 802.11 MAC 1300 and the 802.16 MAC 1305 functions.Separate field programmable gate arrays (FPGAs) could be used toimplement the two PHYs 1310 and 1315. A common set of RF hardware 1320could be used to upconvert/downconvert and otherwise condition thesignals produced by the two PHY modules 1310, 1315, and signals from theRF block 1320 would be passed to/from the antenna 1325. Separate sets ofRF components and antennas may, however, be used for the 802.11 and802.16 functions, and a single FPGA and micro processor used toimplement both of the PHYs 1310, 1315, and the 802.11 and 802.16 MACs1300, 1305.

If the 802.11 and 802.16 functions are collocated at a single station ornode as in FIG. 13, enhanced operation is possible. In particular, if(i) the 802.16 MAC 1305 includes the 802.16 PMP BS node function, (ii)the 802.11 MAC 1300 includes an 802.11 AP node function, and (iii) bothof the MACs 1300, 1305 run from a common timing reference 1330 which inthe present embodiment may be distributed to the MAC components via thePHY components as shown, it is easier to ensure synchronization betweenthe 802.11 and the 802.16 functions. In addition, a bridging (orrouting) function 1335 can be provided as shown for allowing data topass easily either way between the 802.11 and the 802.16 MAC functions.While generally useful in any station that practices both the 802.11 andthe 802.16 protocols, bridging is particularly useful when located in astation or node that will operate as both an 802.11 AP node and an802.16 BS node. This is because a station or node that practices justone of the protocols (802.11 or 802.16) will be allowed to communicatevia the AP/BS nodes with a node that practices only the other protocol.Also, the 802.16 BS node can pass scheduling information 1340 to the802.11 AP node. Recall that in 802.11, a CF-End message can be used toend the CFP when the PCF has no further data, thus allowing timeallocated to the PCF to be recovered for use by the DCF. With the PMPscheduling info available, the AP node may now implement the CF-Endcapability (as shown in FIG. 12 at 1230) to recover time for the DCF(MANET) communications once all current 802.16 PMP communications needshave been met.

Concerning FIG. 13, it is noted as before that PHY1 1310 associated withthe 802.11 MAC 1300, may be a standard 802.11 PHY, or may be an 802.16PHY. It may be easier to implement completely stand alone 802.16 and802.11 configurations, with only timing and bridging functions beingshared in common. In such a case, it may be more convenient to use an802.11 PHY. With some additional effort, an 802.16 PHY can be pairedwith an 802.11 MAC, however. This has an advantage in that the two PHY(PHY1 and PHY2) may be replaced by a single PHY, but compatibility withexisting 802.11 infrastructure may be lost. Other implementation optionswill be apparent to those skilled in the art.

It may also be advantageous to use an 802.11 MAC configured for an IBSSrather than an AP node. Recall that in an IBSS, all stations participatein the Beaconing process. For a MANET, this can be a fairly importantfunction. The stations practicing 802.11 might not always be withinrange of an 802.16 PMP system, so they may want to announce theirexistence periodically. Transmitting a Beacon is a convenient way to doso. Also, an AP node implementing the PCF will not normally include aBeacon contention period. Rather a PIFS time would be used. Thisprevents other stations from sending the Beacon. So it is preferred thatall of the 802.11 MAC provide for Beacon contention. The number ofBeacon contention slots at the beginning of the frame could be a hardcoded network parameter with, e.g., 32 being a preferred implementation.Adaptive techniques that account for the number of 802.11 stations mayalso be applied. An exception to the standard 802.11 IBSS Beaconingprotocol is that all stations transmitting Beacons should include theCFP Parameters. This is not normally the case for Beacons in an IBSS.Because the Beacon size can vary based on the number of elementsincluded, it may be desirable to limit the size of a Beacon message toensure it will fit prior to the 802.16 preamble even if transmitted inthe last Beacon contention slot.

Other optimizations of the 802.11 protocol are possible. For example,the Inter-Frame Space (IFS) and slot size in 802.11 are optimized for a1000 meter maximum range. These values could be modified for moreoptimal operation at larger ranges. One final optimization would be thatif all stations practice the modified version of 802.11 describedherein, the PCF parameters may be hard coded in each station and itwould not be necessary to transmit them.

It is possible further to improve existing MANET protocol sets foroptimized performance in the combined PMP/MANET frame of FIG. 6. TheMANET protocols set may be partitioned into a “Reservation” basedprotocol set, and a “Contention” based protocol set. With appropriatepreplanning, it is possible to rely exclusively on the Reservation basedprotocol set. It is also possible to use only the Contention basedprotocol set which provides increased flexibility, but usually withreduced efficiency. A preferred implementation would combine theContention based protocol set with the Reservation based protocol set,so as to allow optimum flexibility and efficiency.

A further embodiment is shown in FIG. 14, and is referred to herein as a“META-MANET” (MM) frame structure. The structure uses ML Bursts (as alsoshown in FIG. 8) that are scheduled in a manner similar to that used inUSAP. The Bootstrap slots shown in FIG. 8 are replaced by ContentionSlots 1400, however. The slots 1400 are detailed in the part of thefigure termed contention slot details 1405, and are intended for passingcontrol messages, or short data messages. The Contention Slots use OFDMmodulation even if the rest of the frame uses OFDMA modulation, andoperate similar to slots in the “Slotted Aloha” protocol well known inthe art except that the slots 1400 have internal structure that allowsthem to be used for Carrier Sense Multiple Access (CSMA) which is alsowell known in the art and used, for example, in the 802.11 protocol.Five Contention Slots 1400 are shown as a preferred embodiment, but moreor less could be used within the scope of the invention.

The contention slots 1400 are constructed so as to allow either CSMA orSlotted Aloha (or some combination of the two) to be practiced. A TurnAround Time 1410 is allocated at the beginning of the contention slot toallow nodes to change from transmit to receive, or from receive totransmit mode. One quarter of an OFDM symbol is allocated for thispurpose in the preferred embodiment, but more or less may be usedaccording to the invention. A priority opportunity (PO) 1415 is shownthat allows priority messages to be given preferential access to acontention slot when CSMA is practiced. Example messages would be aClear to Transmit (CTS) or an Acknowledgment (ACK), as described in the802.11 protocol. Three quarters of an OFDM symbol time are allocated forthe priority opportunity in the preferred embodiment, but more or lesstime may be allocated. There may also be multiple priorityopportunities, or no priority opportunities, according to the invention.

Following the priority opportunities are a number of contentionopportunities (CO) 1420. The CO 1420 may be used in the same fashion asthey are used within the 802.11 protocol, though other approaches mayalso be used. Three CO are shown as the preferred embodiment, but moreor less may be used. The CO 1420 are shown as one quarter of an OFDMsymbol in size as a preferred embodiment, but larger or smaller sized COmay be used according to the invention. In the preferred embodiment,sufficient time is allocated for three OFDM symbols, two synchronization(sync) symbols, and one data symbol. As would be apparent to one skilledin the art, more or fewer sync and data symbols may be allocated for aCO while remaining within the scope of the invention. Particularly whenpracticing Slotted Aloha, range delay must be accounted. The ContentionSlot 1400 includes an allocation for range delay 1425 which, for thepreferred embodiment, is set to one and a half OFDM symbols, but more orfewer may be allocated within the scope of the invention.

In summary, the various frame structures disclosed and described hereinserve to support both PMP and MANET or mesh protocol wirelesscommunications on a shared set of channels in a common network. In allof the frame structures, a front or leading portion of the PMP frame isreserved for key PMP control fields, and an end portion of the PMP frameis reserved for MANET or mesh control traffic. A PMP base station ornode using the inventive frame structure monitors the MANET/meshscheduling, and schedules PMP traffic around the MANET/mesh traffic. Insome cases a predetermined partitioning could be used. A number ofmechanisms have been described for allocating capacity to the MANET/meshdata traffic in the frame structure.

While the foregoing represents preferred embodiments of the invention,it will be understood by those skilled in the art that variousmodifications and changes may be made without departing from the spiritand scope of the invention, and that the invention includes all suchmodifications and changes as come within the scope of the followingclaims.

We claim:
 1. A method of operating a wireless network for enabling nodesto communicate with one another on one or more shared network channelsor sub-channels according to either a point-to-multipoint (PMP)protocol, or a mobile ad hoc or mesh (MANET/mesh) protocol, comprising:configuring one or more nodes of the network each to operate atdetermined times as a base station or a subscriber station according tothe PMP protocol, and to operate at times other than the determinedtimes according to the MANET/mesh protocol, including: (i) implementingthe MANET or mesh protocol at a given node by using a first mediumaccess control (MAC) component at the node; (ii) implementing the PMPprotocol at the given node by using a second MAC component at the node;(iii) providing control information or data to and from the first andthe second MAC components at the node; (iv) running the first and thesecond MAC components according to a common timing reference; (v)providing the node with a radio frequency (RF) component; (vi) providingthe node with a first physical layer component that is coupled to thefirst MAC component and to the RF component and which is responsive tothe common timing reference, for (a) processing first data input fromthe first MAC component according to the MANET or mesh protocol andoutputting the processed first data to the RF component fortransmission, and (b) processing second data input from the RF componentaccording to the MANET or mesh protocol and outputting the processedsecond data to the first MAC component; (vii) providing the node with asecond physical layer component that is coupled to the second MACcomponent and to the RF component and which is responsive to the commontiming reference, for (a) processing third data input from the secondMAC component according to the PMP protocol and outputting the processedthird data to the RF component for transmission, and (b) processingfourth data input from the RF component according to the PMP protocoland outputting the processed fourth data to the second MAC component;and (viii) bridging the first and the second MAC components with oneanother for passing scheduling information from one of the MACcomponents to the other one of the MAC components.
 2. The method ofclaim 1, including arranging a base station node as a fixed node.
 3. Themethod of claim 1, including arranging a base station node as a mobilenode.
 4. The method of claim 1, including arranging one or moresubscriber station nodes as mobile nodes.
 5. The method of claim 1,including establishing communications using the MANET/mesh protocolbetween a first node of the wireless network and a given node outside ofthe network.
 6. The method of claim 5, including extending the coverageof the first node of the wireless network to the given node by linkingbetween an intermediate relay station node and the first node using theMANET/mesh protocol for coordinating scheduling information, andoperating the relay station node as a PMP base station node with respectto the given node.
 7. The method of claim 1, including defining the PMPprotocol according to the IEEE 802.16 Standard.
 8. The method of claim1, including defining the MANET or mesh protocol according to the IEEE802.11 Standard, and using a point coordination function PCF) beacon andan end of contention free period (CF-END) message according to the802.11 standard to define a time interval for network communicationsunder the PMP protocol.
 9. The method of claim 1, including bridgingcommunications received at a given node under one of the PMP andMANET/mesh protocols, with communications transmitted from the givennode under the other one of the PMP and MANET/mesh protocols.
 10. Themethod of claim 1, comprising: transmitting a downlink signal having atime frame structure of a determined duration from a first node to anumber of second nodes in the wireless network; first allocating one ormore portions of the time frame structure for establishing (i) firsttime periods during which messages are transmitted from the first nodeto the second nodes, and (ii) second time periods during which messagesare transmitted from the second nodes to the first node, using the PMPprotocol on one or more shared channels or subchannels of the network;and second allocating one or more portions of the time frame structurefor establishing third time periods during which nodes communicate withone another using the MANET/mesh protocol on the shared channels orsubchannels while avoiding interference with the messages transmittedunder the PMP protocol.
 11. The method of claim 10, including providinga MANET/mesh scheduler for the wireless network, and establishing thethird time periods in response to reservations of time received at thefirst node from the scheduler for reserving time for MANET/meshcommunications.
 12. The method of claim 10, including establishingcommunications using the MANET/mesh protocol between a first node of thewireless network and a given node outside of the network.
 13. The methodof claim 12, including extending the coverage of the first node of thewireless network to the given node by linking between an intermediaterelay station node and the first node using the MANET/mesh protocol forcoordinating scheduling information, and operating the relay stationnode as a PMP base station node with respect to the given node.
 14. Themethod of claim 10, including establishing the third time periods sothat MANET/mesh communications are scheduled for occurring over not morethan about 50% of the duration of the time frame structure.
 15. Themethod of claim 10, including defining the PMP protocol according to theIEEE 802.16 Standard, defining the MANET/mesh protocol according to theIEEE 802.11 Standard, and using a point coordination function (PCF)beacon and an end of contention free period (CF-END) message accordingto the 802.11 Standard to define a time interval for networkcommunications under the 802.16 standard.
 16. The method of claim 10,including bridging communications received at a given node under one ofthe PMP and MANET/mesh protocols, with communications transmitted fromthe node under the other one of said protocols.
 17. The method of claim1, including: operating one of the nodes of the network as a basestation node under the PMP protocol; operating one or more of the nodesof the network as subscriber station nodes under the PMP protocol;transmitting a downlink signal from the base station node to thesubscriber station node; defining a downlink map in the downlink signalfor scheduling first time periods for transmitting messages from thebase station node to corresponding ones of the subscriber station nodes,and defining an uplink map in the downlink signal for scheduling secondtime periods for allowing a subscriber station node to transmit messagesto the base station node in a scheduled second time period; andallocating a MANET/mesh zone in either one or both of the downlink andthe uplink maps, each zone operating to reserve one or more time slotsand channels or subchannels in which nodes can communicate using theMANET/mesh protocol, while avoiding interference to communications underthe PMP protocol on the reserved channel or subchannels.
 18. The methodof claim 17, including providing a MANET/mesh scheduler for the wirelessnetwork, and carrying out the allocating step in response toreservations of time received at a base station node from the schedulerfor reserving time for MANET/mesh communications.
 19. The method ofclaim 17, including partitioning the downlink and the uplink signalsaccording to a time division duplex (TDD) scheme.
 20. The method ofclaim 17, including defining a time frame for the wireless networkincluding (i) a downlink subframe having a number of successive firsttime slots corresponding to parts of the downlink signal transmittedfrom the base station node, and (ii) an uplink subframe having a numberof successive second time slots corresponding to the scheduled secondtime periods in which subscriber station nodes transmit messages to thebase station node, and allocating the MANET/mesh zones so thatMANET/mesh communications are scheduled for occurring over not more thana desired portion of the time frame.
 21. The method of claim 20,including allocating the MANET/mesh zones so that MANET/meshcommunications are scheduled for occurring over not more than about 50%of the time frame.
 22. The method of claim 1, including providingcontrol information or data to the node with respect to outside devicesrequiring communication services by way of a networking component of thenode.
 23. The method of claim 1, including providing a networkingcomponent at the node, coupling the networking component to each of thefirst and the second MAC components, and configuring the networkingcomponent for routing data to be transported by the node over either alink that follows a MANET or mesh protocol, or a link that follows apoint-to-multipoint (PMP protocol).